Wireless communication systems are widely deployed to provide, for example, a broad range of voice and data-related services. Typical wireless communication systems consist of multiple-access communication networks that allow users of wireless devices to share common network resources. These networks typically require multiple-band antennas for transmitting and receiving radio frequency (“RF”) signals from wireless devices. Examples of such networks are the global system for mobile communication (“GSM”), which operates between 890 MHz and 960 MHz; the digital communications system (“DCS”), which operates between 1710 MHz and 1880 MHz; the personal communication system (“PCS”), which operates between 1850 MHz and 1990 MHz; and the universal mobile telecommunications system (“UMTS”), which operates between 1920 MHz and 2170 MHz.
In addition, emerging and future wireless communication systems may require wireless devices to operate new modes of communication at different frequency bands to support, for instance, higher data rates, increased functionality and more users. Examples of these future systems are the single carrier frequency division multiple access (“SC-FDMA”) system, the orthogonal frequency division multiple access (“OFDMA”) system, and other like systems. An OFDMA system is supported by various technology standards such as evolved universal terrestrial radio access (“E-UTRA”), Wi-Fi, worldwide interoperability for microwave access (“WiMAX”), wireless broadband (“WiBro”), ultra mobile broadband (“UMB”), long-term evolution (“LTE”), and other similar standards.
Moreover, wireless devices may provide additional functionality that requires using other wireless communication systems that operate at different frequency bands. Examples of these other systems are the wireless local area network (“WLAN”) system, the IEEE 802.11b system and the Bluetooth system, which operate between 2400 MHz and 2484 MHz; the WLAN system, the IEEE 802.11a system and the HiperLAN system, which operate between 5150 MHz and 5350 MHz; the global positioning system (“GPS”), which operates at 1575 MHz; and other like systems.
To satisfy consumer demand for multiple-modes and multiple-functions while maintaining or reducing the form factor, weight or both of wireless devices, manufacturers are continually striving to reduce the size of components contained in these wireless devices. One of these components is an antenna, which is required by wireless devices for wireless communication. These wireless devices typically use multiple antennas for operation at various frequency bands. Further, consumer aesthetic preferences typically require that an antenna be contained within the wireless device, as opposed to an external retractable antenna or antenna stub that is visible to the user. It is also desirable to incorporate the antenna within the wireless device for reasons of size, weight and durability. Therefore, antennas typically have been a major focus for miniaturization in wireless devices.
A miniaturized antenna radiating structure, such as a planar inverted-F antenna (“PIFA”), uses a microstrip patch antenna and is typically installed within a wireless device. Patch antennas are popular for use in wireless devices due to their low profile, ability to conform to surface profiles and unlimited shapes and sizes. Patch antenna polarization can be linear or elliptical, with a main polarization component parallel to the surface of the patch antenna. Operating characteristics of patch antennas are predominantly established by their shape and dimensions. The patch antenna is typically fabricated using printed-circuit techniques and integrated with a printed circuit board (“PCB”). The patch antenna is typically electrically coupled to a ground area, wherein the ground area is typically formed on or in a PCB. Patch antennas are typically spaced from and parallel to the ground area and are typically located near other electronic components, ground planes and signal traces, which may impact the design and performance of the antenna. In addition, PIFAs are typically considered to be lightweight, compact, and relatively easy to manufacture and integrate into a wireless device.
PIFA designs can include one or more slots in the PIFA's radiating member. Selection of the position, shape, contour and length of a slot depends on the design requirements of the particular PIFA. The function of a slot in a PIFA design includes physically partitioning the radiating member of a single-band PIFA into a subset of radiating members for multiple-band operation, providing reactive loading to modify the resonant frequencies of a radiating member, and controlling the polarization characteristics of a multiple-band PIFA. In addition to a slot, radiating members of a PIFA can have stub members, usually consisting of a tab at the end of a radiating member. The function of a stub member includes providing reactive loading to modify the resonant frequencies of a radiating member.
Accordingly, a compact multiple-band antenna is a critical component in supporting these multiple-mode, multiple-function wireless devices. It is desirable for an antenna used in a multiple-mode, multiple-function wireless device to include efficient omni-directional broadband performance. It is also desirable for such an antenna to have multiple-band performance, including non-overlapping frequency bands that may be substantially separated in frequency. In addition, it is desirable for such an antenna to be lightweight with a small form factor that can fit within a wireless device. Finally, it is desirable for such an antenna to be low cost, and easily manufactured and installed into a wireless device.
Skilled artisans will appreciate that elements in the accompanying figures are illustrated for clarity, simplicity and to further help improve understanding of the embodiments, and have not necessarily been drawn to scale.